Hard to put them in any order other than popularity without statistics. Gotta be numbers somewhere out there!

It may be possible (but a lot of work) to find listings of top 100 records for each year and then select the folk recording.
It's also possible that a magazine has done a "top 100 of all time" listing. I think I once (years ago) saw a listing like that in Rolling Stone, and it was broken down into top 100 R&B, top 100 country, top 100 folk, etc.